Sema: do not emit `@errorCast` safety check when dest is adhoc inferred error set

Closes #17354

1 files changed, 12 insertions, 0 deletions

diff --git a/test/behavior/error.zig b/test/behavior/error.zig
index 1d5457fa3a..8e4dd2c091 100644
--- a/test/behavior/error.zig
+++ b/test/behavior/error.zig
@@ -1027,3 +1027,15 @@ test "generic type constructed from inferred error set of unresolved function" {
     };
     _ = std.io.multiWriter(.{S.writer()});
 }
+
+test "errorCast to adhoc inferred error set" {
+    const S = struct {
+        inline fn baz() !i32 {
+            return @errorCast(err());
+        }
+        fn err() anyerror!i32 {
+            return 1234;
+        }
+    };
+    try std.testing.expect((try S.baz()) == 1234);
+}